Fin stabilized projectile



1967 MARCUS ETAL FIN STABILIZED PROJECTILE Filed March 25, 1965 INVENTORJ: IRWIN MARCUS BY IRVING KINTISH ATTORNEYS United States Patent ()flfice 3,306,205 FIN STABILIZED PROJECTILE Irwin Marcus, Pompton Plains, and Irving L. Kintish,

Rockaway, N .J., assignors to the United States of America as represented by the Secretary of the Army Filed Mar. 25, 1965, Ser. No. 442,841

1 Claim. (Cl. 102-49) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment tous of any royalty thereon.

This invention relates to a fin stabilized projectile having a normally low velocity over the greater portion of its ballistic. trajectory, and particularly to an improved fin stabilized projectile displayinghigh terminal velocity capabilities.

A low velocity fin stabilized projectile such as a mortar projectile is normally launched in a high are trajectory and strikes a target at a low velocity and consequently a low kinetic energy. Under certain conditions the mortar projectile is ineffective due mainly to this inherent low kinetic energy. As an example, if a heavy enemy emplacement situated on a hillside is the target, a mortar projectile would be ineffective since it would be unable to penetrate this target due to its low terminal velocity. Artillery support or aircraft bombing would be required and in many cases (viz. guerrilla warfare) are not readily available.

Accordingly, it is an object of the present invention to provide a normally low velocity fin stabilized projectile having a high terminal velocity capability.

It is another object of the present invention to provide a normally low velocity fin stabilized projectile in combination with a reaction motor for developing additional thrust necessary to increase the terminal velocity of the projectile.

It is yet another object of the present invention to provide a normally low velocity fin stabilized projectile in combination and integral with a rocket motor, a cooperating proximity sensor and an ignitor for increasing the terminal velocity of the projectile when the projectile comes within a preselected position of a target.

For a fuller understanding of the nature and objects of the invention reference should be made to the following detailed description with the accompanying drawings wherein:

FIG. 1 is a side view partly in cross-section of an embodiment of the present invention;

FIG. 2 is a view showing one manner of using the projectile of the present invention.

Referring to the drawings wherein like reference numerals refer to like parts, throughout,'10 refers generally to the projectile which has a body 12 integral with a nose portion 14 and a tapered rear portion 16. The projectile is a low velocity projectile as the term is used and well known in the projectile art. Typical of a low velocity projectile is a mortar round which is launched from a well known portable tube 18 illustrated in FIG. 2. In order to maintain in-flight aerodynamic stability the projectile has fin stabilizers 20 integrally fixed to its rear end portion.

Within the body 12 and generally centrally disposed is an explosive mixture 22 in an amount suitable to a particular application. The explosive mixture 22 is detonated when the fuze 23 located in the nose portion 14 of the body 1 2 is initiated, that is, when the components of the fuze 23 are made to function to initiate a train of fire which is sufiicient to detonate an explosive or a booster which in turn acts to detonate the explosive. The fuze 23 of this embodiment is an impact delay fuze which functions to detonate a booster 24 by a force of impact. The booster 24 is initiated a short time after impact and 3,306,205 Patented Feb. 28', 1967 it in turn detonates the explosive mixture 22. The fuze 23 is not limited to an impact delay fuze but may be one of many fuzes known and usedthroughout the fin stabilized projectile art. I

Directly behind the fuze 23 is a proximity sensor 26 of-any standard radar type commonly used with a mortar projectile in association with a proximity fuze. The proximity sensor 26 receives a signal from a radar transmitter when the projectile 10 is approaching a desired target. The significance of this will become apparent further on in this description. 7 I, I

A reaction motor 28 which in thisembodiment is a simple rocket motor, is'disposed in the projectile body 12 directly rearwardly of the explosive mixtur e;22. The rocket motor 28 is suitably mounted-by means of brackets 30 or the like fixed to the internal wall of the projectile body 12. The rocket motor 28 is preferably axially aligned with the projectile body 12. A suitable rocket fuel 32 is contained within the rocket motor 28, and may be either solid or liquid as desired. A trap 34 in the form of a frangible or consumable disc is interposed between the fuel 32 and the open ended nozzle 36 of the rocket motor 28. The trap 34 acts to keep the fuel contained within the rocket motor 28 and to prevent any foreign matter from entering therein. As is readily seen from FIG. 1 the rocket motor 28 is positioned to exhaust its burning gases through the open end 38 of the projectile body 12. This will naturally result in a forwardly directed thrust being imparted to the projectile 10.

The rocket fuel 32 is ignited when the electric squib 40 is stimulated by an electrical impulse and the squib 40 in turn fires the igniter 42 which is in operative communication with the fuel 32. The squib 40 is electrically connected through suitable wiring 44 with the proximity sensor 26. The proximity sensor 26 provides the necessary electrical impulse to the squib 40 for firing the igniter 42. As pointed out above, the proximity sensor 26 receives a reflected signal from its own transmitter when the projectile 10 is approaching a desired target.

The operation of this invention may be easily understood by recourse to a hypothetical situation illustrated in FIG. 2, which depicts a heavy emplacement 46 located on a hillside as the desired target. The projectile 10 is launched from a conventional mortar tube 18 by using a standard bagged propellant charge 48. A normal low velocity ballistic trajectory is followed by the projectile. When the projectile reaches the position designated as point A it is in the terminal phase of its ballistic trajectory. At this point the sensor 26 receives a signal reflected from the ground below. The sensor 26 then relays an electrical impulse to the squib 40 which in turn fires the igniter 42. The rocket fuel 32 is thus ignited. A large thrust is developed and is imparted to the projectile thereby increasing the terminal velocity and kinetic energy thereof. The projectile 10, accordingly, has enough energy to drive itself into the emplacement. The impact delay fuze 23 is initiated a short time after contact with the solid surface of the emplacement 46. This allows the projectile 10 to bury itself so that maximum destructive effect of the explosive mixture 22 will be realized. When the fuze 23 is initiated a train of fire results which is directed to the booster 24 through a flash tube 50 wit-h communicates between the fuze 23 and booster 24. The booster 24 is ignited and finally the explosive mixture 22 is also ignited resulting in conveying a desired damaging consequence to the emplacement 46.

We claim:

A low velocity fin stabilized mortar projectile having high terminal velocity capability comprising a projectile body having a nose portion and integrally therewith an open rearward tapered end portion hava booster generally centrally forwardly disposed within said projectile body,

fuze means located within said nose portion operatively communicating with said booster for detonation thereof,

a body of explosive charge disposed in said projectile body operatively associated with said booster,

a separate rocket motor fixedly mounted and wholly enclosed within said rearward end portion of said projectile body disposed axially rearwardly of said explosive charge,

an exhaust nozzle at the rear of said rocket motor axially aligned with said rearward open end portion of said projectile body,

rocket fuel within said rocket motor,

means for igniting said rocket fuel after said projectile has started its downward trajectory to impart high terminal velocity to said projectile; and

References Cited by the Examiner UNITED STATES PATENTS 1,994,490 3/1935 Skinner 102-49 2,701,527 2/1955 Granath et al. 102-75 2,767,657 10/1956 Burke 102-49 2,804,823 9/ 1957 Jablansky 102-49 2,870,710 1/1959 Miedel 102-4) BENJAMIN, A. BORCHELT, Primary Examiner.

20 V. R. PEND'EGRASS, Assistant Examiner. 

